AMD Posts Latest Revision To Its New P-State Linux Driver

Written by Michael Larabel in AMD on 29 October 2021 at 11:13 AM EDT. 13 Comments
In early September AMD posted their new "amd-pstate" CPU frequency scaling driver for Linux that leverages ACPI CPPC data available with Zen 2 and newer processors for making wiser frequency scaling decisions. The goal of AMD P-State is to offer better performance-per-Watt and today they have posted a new revision of this driver.

In late September AMD posted the amd-pstate v2 patches while now in ending out October they have posted amd-pstate v3. With this updated patch series, they still are limiting the driver compatibility to select Zen 3 processors while with time they plan to broaden it up to the rest of the Zen 2 and Zen 3 processors.

New to the amd-pstate v3 series is a patch from Valve to allow using SystemIO for _CPC registers. This patch should help some platforms like the ASUS Zephyrus G15 that use a SystemIO register for the highest performance _CPC element. The v3 patches also have a variety of fixes, updated documentation, cleaning up some of the APIs, clearing up some elements of the sysfs interface, and other updates.

The amd-pstate v3 patches are out for review and testing on the kernel mailing list. Though given the timing of these patches and still needing to undergo a fresh round of review, it's probably unlikely to see this driver land for the upcoming Linux 5.16 merge window especially if it does indeed open up on Sunday rather than being pushed back by one week. That's too bad for this driver, which was developed in cooperation with Valve as part of the Steam Deck and other AMD Linux developments, but hopefully it will get ready for mainline by the 5.17 cycle.
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